Cleanup at end of TLS test by freeing slot
Cleanup at end of TLS test by freeing slot

I noticed that all threads in the unit tests that
run after the TLS test call the TLS test destructor
as their threads go away.  This interaction between
tests doesn't seem good... so I added a free call.

r=darin
Review URL: http://codereview.chromium.org/8507015

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@109446 0039d316-1c4b-4281-b951-d872f2087c98

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